Hydraulic soil failure due to artesian ground conditions during the construction of a hydro electrical power plant on Sakarya river

The presence of an artesian aquifer lying under the construction site of a hydro-electrical power plant had not been considered in the design project. The foreseen excavation works could not be carried out due to a high risk of hydraulic heave of the excavation pit bottom and the entire plant had to be relocated. In the scope of this thesis, two alternative solutions to deal with the local artesian conditions are suggested. The first solution considers additional resisting shear forces coming from cohesion in clayey soils, whereas in usual design approaches for hydraulic heave problems only the equilibrium between gravity forces and seepage forces is established. Cohesion plays an important role for the stability of relatively small excavation pit widths and its beneficial effect could be used by applying a stepwise excavation process. The second solution suggests a local relief of artesian pressures in the zone of the construction site in order to temporarily create a neutralized zone until the power plant is completely built.